In the bravura wedding scene that opens director Francis Ford Coppola's The Godfather, brother of the bride, Sonny Corleone (played by James Caan), pinches the cheek of bridesmaid Lucy Mancini (Jeannie Linero) and later slips off with her for a clandestine liaison. From these few brief scenes, you'd never know that Lucy is a fully developed character in Mario Puzo's novel of the same name: she helps set up the Corleone family operations in Las Vegas, and the book explores her grief after Sonny's assassination and her journey back to romantic and sexual happiness.

I think about Lucy Mancini a lot, not so much because her story is a major loss to movie history, but because she represents the women on the margins who bear the consequences of the main character's decisions. And she was never on my mind so frequently as when I watched HBO's adaptation of My Brilliant Friend, the first novel in Elena Ferrante's Neapolitan quartet, which debuted Sunday. It would be a disservice to My Brilliant Friend to treat it as a mere addendum to The Godfather. But watching the movie series and the miniseries together is a powerful testament to what we gain when we see the world both from the centre and the margins.